It is known that large diesel engines in particular are increasingly equipped with double-flow air systems. Two turbochargers compress both fresh air mass flows to a common boost pressure. The exhaust gas mass flows drive the turbines of both turbochargers.
German Patent Application No. DE 100 10 978 describes a method for regulating the boost pressure of an internal combustion engine having an exhaust gas turbocharger. A specified exhaust gas back pressure is established by a first controller from the difference between a specified boost pressure and an actual boost pressure, and the manipulated variable for the turbine geometry of the exhaust gas turbocharger is derived by a second controller from the difference between the specified exhaust gas back pressure and a measured or estimated actual exhaust gas back pressure. In this manner, a cascade controller is implemented. The cascade controller permits the exhaust gas back pressure to be limited and, at the same time, the regulating response to be improved.